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Hydroelectric turbine runners (blades) are very efficient at extracting the energy from a fast moving water current (high head) but not very efficient with slower currents (low head). The reason for this problem is that existing runners (blades) rotate around a central shaft which restricts their ability to have very large diameters due to weight and structural limitations. Low head currents contain less energy per a given cube of water and therefore require a larger blade surface area. This invention deals with this situation in three basic ways.
1. By eliminating the central area of the blade where the most weight and drag occur.
2. By taking the energy from the blade perimeter (outer blade tips).
3. By designing the blades of very large diameters to also have larger open areas in their centers.
By incorporating the above 3 ideas, the invention can be built ever larger which gives the large blade area needed for low head applications while holding weight and drag to a minimum. In essence, the hole in the center continues to get larger which increases the blade area accordingly but the structural limitations, weight and drag are held to a minimum.
The invention is a machine designed to be capable of having a very large blade area while eliminating some inherent problems of existing blade technologies. This is accomplished by taking the energy of the blade from the periphery and not a central shaft. This is seen in U.S. Pat. No. 5,592,816 HYDROELECTRIC POWERPLANT. While that patent incorporates a hydraulic system to take the energy from the blade to the generator, this machine takes the energy from the blade to a generator (or generators) by the use of a mechanical means thereby eliminating the hydraulic system altogether which allows for the blades to be built very large in size.